With reference to FIG. 10 through FIG. 12, a standby operation of a mobile station UE in a mobile communication system imparted with an EPC (Evolved packet Core) network incorporating a radio access network of a WCDMA scheme and a radio access network of an LTE (Long Term Evolution) scheme is explained. FIG. 10 shows a configuration and an outline of an operation of the mobile communication system.
Firstly, with reference to FIG. 11, an example of an operation when the mobile station UE attempts to perform a location registration process in the radio access network of the LTE scheme is explained.
As shown in FIG. 11, the mobile station UE establishes an RRC (Radio Resource Control) connection with a radio base station eNB in step S3001, and then in step S3002, it transmits an “Attach Request” to a mobile switching center MME.
After performing a process for authentication and ciphering of the mobile station UE between the mobile station UE and the mobile switching center MME in step S3003, the mobile switching center MME transmits an “Update Location Request” to a subscriber management server device HSS in step S3004.
In step S3005, based on the contract information of the mobile station UE, the subscriber management server device HSS determines “RFSP (RAT Frequency Selection Priority)” showing the “RAT (Radio Access Technology, radio access network)” for which the mobile center UE must preferentially perform the standby operation.
In step S3006, the subscriber management server device HSS transmits an “Update Location Answer” including the RFSP to the mobile switching center MME.
In step S3007, the mobile switching center MME extracts “SPID (Subscriber Profile ID for RAT/Frequency Priority)” corresponding to the RFSP included in the received “Update Location Answer”, and then in step S3008, it transmits an “Initial Context Setup Request” including the extracted SPID to the radio base station eNB.
In step S3009, the radio base station eNB performs a standby RAT instruction for the mobile station UE based on the SPID included in the received “Initial Context Setup Request”.
Secondly, with reference to FIG. 12, an example of an operation when the mobile station UE attempts to perform a location registration process in the radio access network of the WCDMA scheme is explained.
As shown in FIG. 12, the mobile station UE establishes an RRC connection with a radio network controller RNC in step S3101, and then in step S3102, it transmits an “Attach Request” to a mobile switching center SGSN.
After performing a process for authentication and ciphering of the mobile station UE between the mobile station UE and the mobile switching center SGSN in step S3103, the mobile switching center SGSN transmits an “Update GPRS Location” to the subscriber management server device HSS in step S3104.
In step S3105, based on the contract information of the mobile station UE, the subscriber management server device HSS determines “RFSP” showing the RAT for which the mobile center UE must preferentially perform the standby operation.
In step S3106, the subscriber management server device HSS transmits the “Insert Subscriber Data” including the RFSP to the mobile switching center SGSN, and after receiving its response, it transmits the “Update GPRS Location Ack”.
In step S3107, the mobile switching center SGSN extracts the SPID corresponding to the RFSP included in the received “Insert Subscriber Data”, and then in step S3108, it transmits a “Direct Transfer” including the extracted SPID to the radio network controller RNC.
In step S3109, the radio network controller RNC performs a standby RAT instruction for the mobile station UE based on the SPID included in the received “Direct Transfer”.
However, the aforementioned mobile communication system had a problem in that due to the fact that the standby RAT of each mobile station UE is determined based on the contract information of each mobile station UE, it is not possible to achieve high-speed connection time when the standby RAT of a mobile station UE that does not support CS (Circuit Switch) communication is a radio access network of the LTE scheme, and it is also not possible to reduce the sending and receiving time of CS communication when the standby RAT of a mobile station UE equipped with a CSFB (CS Fallback) function is a radio access network of the WCDMA scheme.